Evaluation of the anaplasmosis rapid card agglutination test for detecting experimentally-infected elk.

Anaplasma marginale was experimentally transmitted from cattle to elk to cattle. Six intact adult elk (Cervus canadensis canadensis) inoculated with freshly collected heparinized blood from cattle chronically infected with A. marginale became asymptomatic carriers. Although the elk did not develop clinical or hematologic evidence of infection, they became seropositive by the serum(SRCA) and plasma rapid card agglutination (PRCA) tests. Blood from the experimentally-infected elk produced disease in splenectomized bovine calves and the carrier state persisted for at least one year. Infection did not occur when two elk were inoculated with 0.5 ml of frozen blood from known bovine carriers. The blood had been frozen for four weeks in liquid nitrogen with 6% dimethyl-sulfoxide. The bovine SRCA and PRCA tests were adapted for use with elk serum. To obtain accurate test results, serum collected from clotted elk blood had to be held for at least 72 h at 21-27 C before performance of the SRCA test. Comparative serologic and infectivity studies indicated that the carrier (reactor) status of elk was accurately identified with the serologic tests in 61 of 68 samples evaluated. Incorrect serologic results with the SRCA and PRCA tests were false-negative readings. In no case were uninfected elk identified as seropositive.

The immobilization of wapiti with etorphine hydrochloride.

Data and observations on the use of Etorphine hydrochloride (M99) (in combination with Acepromazine) and its antagonist M50-50 for immobilization of captive elk (Cervus elaphus canadensis) are presented. The study period covers 3 years during which 8 adult elk were immobilized 52 times with M99. The average dose of M99 administered for each immobilization was 2.2 mg per 100 kg body weight. Reversal with M50-50 was effected by an average dose of 4.4 mg per 100 body weight. Induction averaged 5.9 minutes while reversal took an average of 4.6 minutes.

Evaluation of free-roaming mule deer as carriers of anaplasmosis in an area of Idaho where bovine anaplasmosis is enzootic.

Samples of blood from 87 Rocky Mountain mule deer (Odocoileus hemionus hemionus) were inoculated into 3 susceptible splenectomized calves to determine the anaplasmosis carrier status of the deer. The deer were trapped along the Idaho-Utah state boundary, near Stone, Id. Acute anaplasmosis was induced in 2 of the 3 inoculated calves, and blood from the 3 calves caused anaplasmosis when inoculated into adult non-splenectomized cattle. Serum rapid card agglutination testing revealed 13 (14.9%) positive reactions among the 87 mule deer. When these seropositive samples were evaluated with the complement-fixation test, positive reactions were not found and only 3 (3.5%) serums gave suspect reactions. A serologic survey for anaplasmosis in 1,852 cattle that cohabit spring and summer rangeland areas with mule deer revealed 14.5% reactors by the serum rapid card agglutination test. The study area consisted of an ecosystem that supports cattle, free-roaming mule deer, and Dermacentor andersoni, and thus contained the elements necessary to effect interspecies transmission of Anaplasma marginale. The significance of wildlife reservoirs and their bearing on anaplasmosis control and eradication programs needs further investigation.

Survey of anaplasmosis in elk of the Clearwater National Forest (Idaho).

Samples of blood from 27 free-roaming elk (Cervus canadensis canadensis) from the Clearwater National Forest in north central Idaho were tested by the rapid card agglutination test and complement-fixation test for the presence of antibodies against Anaplasma marginale. The serum card test and complement-fixation test gave incomplete and false-positive reactions; the plasma card test did not give any reactions. Anaplasma bodies or other blood parasites were not observed in stained smears of elk blood. Blood from 11 elk, including 2 that were serum card test-positive, did not produce clinical, hematologic, or serologic evidence of infection in 3 anaplasmosis-susceptible bovine calves.

Effect of five daily intravenous treatments with oxytetracycline hydrochloride on the carrier status of bovine anaplasmosis.

Intravenous administration of oxytetracycline hydrochloride at the rate of 22 mg/kg daily for 5 days was effective in rendering parasite-free 11 adult cattle that were naturally infected Anaplasma marginale carriers. The treatment did not cause any noticeable distress or side effect. Through 12 posttreatment months, the efficacy of the treatment procedure was evaluated by serologic tests and subinoculation of blood into susceptible splenectomized calves. Results of the rapid card agglutination test were positive for 5 cattle at 2 months after treatment, but negative for all cattle at 4 through 12 months. Complement-fixation titers were variable and transient in posttreatment serologic studies. After subinoculation of blood into splenectomized calves (at 4 and 12 months after chemotherapy), serologic, hematologic, or clinical evidence of infection with A marginale was not seen during a 60-day observation period.